systemd-cgls

firefox
top -- using 4% of memory

cat /usr/lib/systemd/system/firefox.service
cat /usr/lib/systemd/system/firefox.slice

sudo systemctl start firefox.service
top -- using 2% of memory
sudo systemd-cgls
sudo systemd-cgtop

Note CONFIG_MEMCG=y.
ls /sys/fs/cgroup/memory/firefox.slice/firefox.service
cat /sys/fs/cgroup/memory/firefox.slice/firefox.service/memory.limit_in_bytes



